(a) Field of the Invention
The present invention relates to a tuning device for a radio receiver, and more particularly to a tuning device arranged so that a tuning element can be driven by a motor also, in addition to manual tuning.
(b) Description of the Prior Art
As is well known, automatic tuning in radio receivers is performed by mechanically driving, by a motor, a tuning variable capacitor of a high frequency amplifier circuit and a variable capacitor for varying the oscillation frequency of a local oscillator circuit (hereinafter these capacitors will be referred to simply as tuning variable capacitors), and by electrically detecting the condition of the tuning variable capacitors and thereby controlling the rotation of the motor in accordance with the detection output signal. In such an operation, there has been produced with relative ease, an electrical processing circuit for producing a signal for controlling the motor in accordance with a signal indicating the detected tuning condition. However, with respect to the system for mechanically transmitting the rotation of the motor of the variable capacitor, the system has been unsatisfactory with respect to precision, response and operability.